Add security middleware, audit log, alerts, PayPal, cron, radio + apps

Security (launch blockers):
- src/middleware.ts (edge): forwards x-pathname + real client IP.
- access-guard.ts (Node, from root layout): routes non-staff to /maintenance
  when maintenance mode is on, banned users to /banned. New /banned + /maintenance
  pages (the consumers the admin toggle was missing). Admin layout enforces
  force_staff_2fa before /admin.
- staff-activity.ts audit log wired into ban/lift/give-currency/set-rank actions.

Infra (parallel agents): alert service (alert_logs + Discord embed + email),
PayPal top-up (create/capture API routes + /shop/topup), cron worker
(scripts/jobs-worker.ts via croner: emulator-ping->alert, maintenance-check,
bans-cleanup), social connections page, admin radio settings/banners/ranks.
Public radio subsystem: /radio (+schedule, shouts+post, contests, giveaways,
apply, leaderboard) and /apply/staff + /apply/team submission forms. Radio nav
link added. .env.example documents the new optional vars.

(radio song-requests dropped: its table is a stub in AtomCMS — columns added by
un-modeled alter-migrations.)

Verified: tsc exit 0, vitest 48/48, next build exit 0 (82 page routes).

src/app/maintenance/page.tsx

@@ -0,0 +1,23 @@
+import { siteSettings } from "@/lib/services/site-settings";
+
+export const dynamic = "force-dynamic";
+
+export default async function MaintenancePage() {
+  const [hotel, message] = await Promise.all([
+    siteSettings.get("hotel_name", "Atom"),
+    siteSettings.get(
+      "maintenance_message",
+      "We are currently performing maintenance. Please check back soon.",
+    ),
+  ]);
+
+  return (
+    <main style={{ maxWidth: 540, margin: "2rem auto" }}>
+      <div className="card" style={{ padding: "1.75rem", textAlign: "center" }}>
+        <h1 style={{ marginTop: 0 }}>{hotel} is under maintenance 🛠️</h1>
+        <p>{message}</p>
+        <p className="muted">Staff can still log in.</p>
+      </div>
+    </main>
+  );
+}